This article considers Angela Kerins v John McGuinness, a 2019 case decided by the Irish Supreme Court concerning the justiciability of parliamentary proceedings. It is in four parts. The first two are descriptive: one presents the important facts of Kerins; the other, the relevant constitutional text and precedents. Part III assesses how, in light of the text and precedents, the judges approached the question of justiciability in the case. It gives some consideration to the approach taken to the same question in Denis O’Brien v Clerk of Dáil Éireann, a related case decided in the same period, and in tandem, by the same seven judges. The concluding part offers analysis of the coherence and implications of this jurisprudence.